Consider the unbalanced equation: sio2(s) c(s) → sic(s) co(g) balance the equation and calculate how many moles of carbon are needed to make 2.5 moles of sic.

Hello!

Here from the unbalanced reaction we can balance it by comparing the reactants and products(Left hand side versus Right hand side). We can see one carbon and two oxygen on the left hand side, but then we have two carbon and only 1 oxygen on the rhs. This goes against matter or energy can be neither created or destroyed so we have to balance it first to compare mole to mole relationships. So we can simply right in the the missing elements and balance like this:

SiO2(s) + 2C(s) —-> SiC(s) + C02(g)

Now from the balanced reaction we can see it takes 2 moles of Carbon to make only 1 mole of SiC. So if we are given the amount of moles Of SiC produced, then we can see from the 2:1 Ratio of Carbon:SiC that we need double the amount of Carbon to produce 1mole of SiC(s) since the Carbon used is making SiC(s) and CO2(g). Therefore we would need 5moles of Carbon to start with, in order to make 2.5mole of SiC and CO2 from the reaction given above.

Hope this helps. Any questions please feel free to ask. Thank you kindly!